Distance measuring device



Sept. 29, 1942. E. BRULIN 2,297,534

DISTANCE MEASURING DEVICE Filed Aug. 13, 1941 2 Sheets-Sheet 1 INVENTOR79 Edvard Bra [Z a I 'NESBES x TTORNEYS Sept. 29, 1942.

E. BRULIN DISTANCE MEASURING DEVICE Filed Aug. 13, 1941 Sheets-Sheet 2 aM I MXFT'BENEYG Patented Sept. 29, 1942 UNITE DISTANCE MEASURING DEVICEEdvard Brulin, Brooklyn, N. Y., asslgnor of onehalf to Olson Bros.Machine, Tool and Saw 00., Inc., Brooklyn, N. Y., a corporation of NewYork 7 7 Application August 13, 1941, Serial No. 406,669

3 Claims.

This invention relates to a measuring device for measuring the distancebetween two objects.

Although my device may have many different uses, it is particularlyadapted for use on an aircraft to measure the distance or altitude ofthe aircraft above the ground. Many of the altimeters now in useindicate the altitude of the aircraft above sea level. However, as apractical matter, it is more important for the pilot to be apprised ofthe distance of the aircraft above the ground.

It is an object of the present invention to provide an improvedautomatically operable device for instantaneously indicating thedistance of the aircraft above the ground, and which will immediatelyrespond to any variation in distance and indicate the new or correcteddistance.

A further object is the provision of improved apparatus of the abovecharacter using a reflected beam coming from a source of energy,directed at a known angle whereby the distance of the aircraft or otherobject from the reflecting surface can be calculated by the angle atwhich the beam impinges upon the aircraft.

A further object is the provision of an improved distance measuringdevice using a beam of spectral energy which will operate during fogsand adverse weather conditions, and which will only respond to a. beamof the type coming from the controlled source of energy and will notrespond to other types of beams.

A further object is the provision of a distance or altitude indicatingdevice of simplifled construction and having relatively few movingmechanical parts whereby the device may be used for relatively longperiods of time with comparative freedom from wear.

In the accompanying drawings- Fig. 1 is a side elevation partiallyfragmentary, showing an altitude or distance indicating device embodyingmy invention, applied to an airplane;

Fig. 2 isa circuit diagram of the circuits which 'may be employed inconnection with my device and showing the source of light or otherspectral energy and the receiving device in section;

Fig. 3 is a cross sectional view of the beam receiving device andassociated parts in the direction of the arrows on the line 3-3 of Fig.2; and

Fig. 4 is an elevational view from one side of In the drawings I haveindicated my device as applied to an airplane 5, of conventionalconstruction, and which, per so, does not constitute my invention. Onthe airplane I mount both a source of light or other spectral energy,and a receiving device for receiving the reflected rays of the beam oflight or spectral energy. E

The light source may take the form of a lamp 6, mounted in a casing I,provided with a lens 8 at the lower end thereof. The casing l is mountedin the plane at a controlled predetermined angle so as to direct thebeam of light or spectral energy. downwardly towards the ground at anangle approximating the angle shown in Fig. 1'. The lamp is preferablyan infra-red ray lamp so that its beam will penetrate fogs and the likeand it is connected by a lead 9 to one side of a source of electriccurrent, and by lead I0 to the other side of the source of electriccurrent.

The electric current employed for the lamp 6 is preferably alternatingcurrent, of a known fre quency as, for instance, thirty cycles persecond. By using alternating current of this character, and by using theadditional light receiving mechanism hereinafter described, my distancemeasuring device will only respond to light coming from the lamp 6 andwill not respond to a light having a different frequency.

The light source is preferably mounted near one end of the plane as, forinstance, the tail of the plane, and plvotally mounted adjacent theopposite end of the plane is a light receiving device for receiving raysof light reflected from the ground. The light receiving device comprisesa hood ll supported on one side by a yoke l2, connected to shaft 14journaled in flxed bracket l5. On its opposite side, the hood isprovided with a bearing l6 which engages and may rotate about the shaftll. It will thus be seen that hood ll, yoke l2, and shaft l4 may pivotor rotate around a horizontal axis passing through the shafts l4 and IT.

The hood is divided into three compartments, l8, l9 and 20, the centralcompartment l9 being elongated and relatively narrow, and the outercompartments l8 and 20, preferably flaring outwardly in the mannershown. The hood is so mounted on the airplane as to pivot towards andaway from the light source. Since, in the illustrated embodiment, thelight source is mounted in the tail of the ship and the hood-is mountednear the front of the fuselage,.the hood will pivot longitudinally ofthe ship. The hood should be of such a size and the light source shouldbe directed at such an angle that rays of light, re-

fiected from the spot of light formed by the impinges upon the lowerground level M at the point or spot 24 and a ray is reflected upwardlyalong the line 25 to the hood. The beam 23 impinges upon the higherground level at the point or spot 25, and a ray of'light is reflectedalong the line 2'! to the hood.

In both instances, when the hood ii is depending downwardly in itsnormal vertical position, shown in Figs. 2 and 4, the rays 25 and 2!reflect into the first compartment 53. When the spot of light ispositioned immediately beneath the central portion of the hood, it willreflect upwardly into the compartment it, when the hood is in its normalposition. When the altitude of the airplane is further increased so thatthe spot of light is positioned in front of the hood, a ray of lightwill reflect upwardly into the compartment 20, when the hood isdepending downwardly.

in its normal position.

In association with the hood H, I provide improved mechanism whereby thecentral portion of the hood is always caused to point towards the spotof light on the ground, when the device is in operation, and since thelight source is adjusted to a fixed angle, the angle of the hood willalways accurately indicate the distance or altitude of the aircraft innormal horizontal position above the ground. In this connection, Ipreferably provide a suitable indicating dial, such as the pointer 28,fixedly mounted on the shaft I4 so as to rotate therewith, and a fixeddial face 23, having altitude markings formed thereon and positionedadjacent the pointer 23. The'dial face is attached to the fixed bracketi5, and in this way it will be seen that, as the angle of hood itvaries, the angle of pointer 28, with respect to the dial face, willsimilarly vary so as to indicate the altitude or distance of the planeabove the ground.

The mechanism whereby the hood is caused to automatically point towardsthe spot of light on the ground, coming from the light beam 23,comprises the photo-electric cells 33, 3i and 32, positioned adjacentthe upper edges of compartments i3, i9 and 20, and connected in the gridcircuits of the amplifier tubes 33, 34 and 35 which, in turn, areinductively coupled as by the transformers 36, 37 and 38, to thecircuits of the relays 39, 40 and M. Relay 39 controls the circuit ofcoil 42. Relay 4! controls the circuit of coil 43,

and relay 4!] controls the circuit of solenoid 44. The coils 42 and 43are disposed around the permanent magnets and 46, respectively,

which are fixedly mounted on the yokes 41 and are in the form of arcsdrawn from a center conforming with the axis of rotation of hood H. Thepermanent magnets have fixed poles which, in the illustrated embodiment,are arranged with the north poles toward the top, and the south polestowards the bottom. When coils 42 and 43 are energized, they areattracted towards the north poles of the respective magnets. In thisconnection it will be appreciated that coils 42 and 43 are of the typewhich have two south Poles, 1. e., one at each end, and a north pole atthe central portion. To accomplish this, the winding at one end of eachcoil is in a clockwise direction, and at the other end in acounterclockwise direction.

In Figs. 1 and 2, coils 42 and 43 are mounted upon yoke l2 which rotatesor pivots with hood l I. Thus, when coil 42 is energized, the entirehood is caused to rotate or pivot in a clockwise direction, as viewed inFigs. 1 and 2. When coil 43 is energized, the entire hood is caused torotate or pivot in a counter-clockwise direction, as viewed in thesefigures. Solenoid 44 is provided with an armature 48 having a brakeblock 49 secured to the end thereof and adapted to engage a brake drum50 on shaft I4 and prevent further rotation thereof when the solenoid isenergized and attracts the armature towards it. Due to this arrangement,it will be seen that when the light beam 23 impinges upon the ground soas to form a spot to the rear of hood II, as shown at 24 and 26 in Fig.l, a ray of light from the spot will reflect against the photo-electriccell 30 in compartment l8, and through the medium of amplifier tube 33and relay 33, will energize coil 42, causing the hood to pivot in aclockwise direction, as viewed in Figs. 1 and 2. When the centercompartment l9 faces towards the spot of light so that a ray of light isdirected upon the photo-electric cell 3i, solenoid 44 will be energized,with the result that brake 48 will be applied, locking the hood in aposition directed towards the spot of light.

Since the lamp 3 and casing 1 are disposed at a predetermined angle, andthe markings on dial plate 29 have been properly calibrated inaccordance with that angle, dial 28 will accurately indicate thealtitude of the airplane. It will be appreciated that when the spot oflight is formed in front of the hood, a ray of light will reflect uponphoto-electric cell 32, with the result that the hood will be caused topivot in a counterclockwise direction, as viewed in Figs. 1 and 2, untilthe center compartment I9 is directed towards the spot, at which time alight ray will impinge upon photo-electric cell 3!, causing theoperation of the brake. When the elevation of the plane above the groundvaries, due to irregu other reason, the hood will automatically vary itsposition so that the center compartment thereof points towards the spot.Accordingly, my improved device will always accurately register theheight of the airplane above the ground.

A wiring diagram whereby the desired results can be obtained is shown inFig. 2, wherein it will be seen that the photoelectric cells areconnected in so-called "forward circuits" with the amplifier tubes.Thus, at one side, the photoelectric cells are connected by leads 5i, 52and 53, to the positive side of a source oi electric current.Photo-electric cell 30 is connected by lead 54 to the grid of tube 33,while photo-electric cell 3| is connected by lead 55 to the grid of tube34, and photo-electric cell 32 is connected by lead 56 to the grid oftube 35. The filament of each tube is connected directly to the ne ativeside of the source of electric current, while the grids of the tubes areconnected through resistances 51, 58 and 59 respectively, to thenegative side of the source of electric current.-

One end of the primary winding of transformer 38 is connected by lead 5|to the positive side, while the other end of the winding is connected bylead 60 to the plate or tube 33. One end of the primary winding oftransformer 31 larities on the surface of the ground, or for aii'fi isconnected by leads SI, 52 and GI to the positive side of the source ofelectric current, while the other end of the winding is connected bylead 62 to the plate or tube 34. Similarly, one end of the primarywinding of transformer 38 is connected by leads 5!, 52 and 63 to thepositive side "ends orthe wi d n o r lax Relays 39, t and M control theoperation of switches ii, Hand 73 which are disposed in the circuits ofthe coils 42 and 43 and the solenoid M. Thus, it will be seen that oneof the terminals of switch Ii is connected by leads M and E to thenegative side of a source of electric current, while the other terminalof switch H is connected by lead 16 to one end of the winding of coil42. Similarly, one terminal of switch 12 is connected by leads ill and15 to the negative side of a source of electric current,

while the other terminal is connected by lead 18 to one end of thewinding of solenoid M. One terminal of switch 13 is connected by leadsi9 and 15 to the negative side of the source of electric current, andthe other terminal is connected by lead 8b to one end of the winding ofcoil 43. The circuits of the coils E2 and t3 and of solenoid M arecompleted through leads 8!, 82 and 83, switch M and lead d5, whichconnects to the positive side of the source of electric current. Switch84 is controlled by relay 86.

From the circuits just described, it will be seen that when switch 84 isclosed so as to complete the connection between the coils t2 and 53 andsolenoid it, and the positive side of the source of electric current,the operation of relay 3% to close switch M will complete the circuit ofcoil 62. Similarly, the operation of relay it to close switch '52 willcomplete the circuit of sole noid M, and the operation of relay ii toclose switch i3 will complete the circuit of coil 63.

In the illustrated embodiment of my invention, I have shown anarrangement whereby the receiving device will respond only to lightbeams similar to those emanating from lamp t. This is accomplished byemploying alternating cur- J rent to energize the lamp 6. Thealternating current has a predetermined number of cycles per second as,for instance, thirty, with the result that the beam from the lamp willoscillate or fl cker a predetermined number-of times. 'Relay 3b isdisposed in the circuit of the secondary winding of transformer ti whichis connected in series with the lamp ii. The relay is a polarized.

relay, with the result that switch at is caused to open and close thesame number of times as the lamp is caused to osciilate.

Similarly, relays 3t, ill and M are polarized relays in which theswitches are caused to open or close, depending upon the direction ofcurrent flow through the windings of the relays. When alternatingcurrent flows through any one of the relays 39, Ml and M, the switchesii, '12 and it will be caused to alternately open and close. When anyone of these switches operate in synchronism with switch 85, it will beseen that the circuit of coil 42 or of coil 63 or of solenoid 44 will beintermittently energized. If the operation of relays 39, 40 and M arenot in synchronism with relay 86, the coils 42 and 43 and solenoid Mwill not be energized. Thus it will be seen that when one of thephoto-electric cells 30 is focussed upon a ray of light reflected fromthe light beam coming from lamp 6, it will create electrical impulsescorresponding to the number of cycles of the alternating currentemployed, and due to the inductive coupling between the amplifier andthe relays 39, 40 and M,

these relays will be energized by alternating current in synchronismwith the alternating current operating the lamp.

Should a constant light beam become focussed upon one of thephoto-electric cells, the relays 39, 40 and M will not be energized, dueto the inductive coupling" between the amplifiers and" relays. Also, ifa light beam having a different number of cycles becomes focussed uponone of the photo-electric cells, it will not interfere with the device,due to the fact that the relays 39, 40 and GI will not operate insynchronism with relay 8G to close the circuit of one of the coils 42 or43 or solenoid M.

It should be understood that the relays and amplifier tubes may beenclosed in suitable casings. Thus, the relay 86 may be enclosed in acasing 90. The relays 39, t0 and 4| may be enclosed in a casing 9 I, andthe amplifier tubes maybe enclosed in a casing 92.

It will thus be seen that I have provided an improved distance measuringdevice for measuring the distance between two objects, particularly formeasuring the distance or altitude of an aircraft above the ground. Thedevice is automatically operable so as to constantly indicate thedistance of the aircraft above the ground, and has a minimum of movingparts so that it will not readily get out of order. It should beunderstood that the expressions light, light beam and beam as usedherein, refer not only to visible light, but also to other spectralenergies such as infra-red rays. It should also be understood thatmodifications may be made in the illustrated and described embodiment ofmy invention without departing from the invention as set forth in theaccompanying claims.

I claim:

l.- A device for measuring the distance between 'two objects comprisinga light beam source mounted on the first object for directing a lightbeam at a predetermined angle towards the second object to form a spotof light thereon, a light receiving hood pivotally mounted on the firstobject and having a plurality of compartments open at one end thereofand closed at the opposite end and adapted to receive a ray of lightreflected from the spot on the second object, and means includingphoto-electric cells mounted adjacent the closed ends of thecompartments respectively and electrically operated apparatus connectedto the photo-electric cells and controlled thereby for causing the lightreceiving hood to pivot in different directions when a ray of lightimpinges upon different photo-electric beam at a predetermined angletowards the sec-- ond object to form a spot of light thereon, a lightreceiving hood pivotally mounted on the first ohject and dividedlongitudinally into three compartments open at one end and closed at theopposite end and adapted to receive a ray of light reflected from a spoton the second object, and means including photo-electric cells mountedadjacent the closed ends of the compartments respectively,electro-magnetic means controlled by the photo-electric cells on the twooutside compartments for causing the light receiving hood to pivot whena light ray impinges upon the said photo-electric cells, and a brakecontrolled by the photo-electric cell in the intermediate compartmentfor preventing pivoting of the light receiving hood when a ray of lightimpinges upon the intermediate photo-electric cell whereby the lightreceiving hood is caused to assume a predetermined angle with respect tothe spot of light on the second object.

3. In a device of the character described, a light beam source mountedon a first object for directing a light beam towards a second object andform a spot of light thereon, a circuit including a source of electriccurrent for supplying an alternating current of predetermined frequencyto said light beam source whereby the light beam operates at apredetermined frequency, light sensitive means mounted on the firstobject for receiving a ray of light reflected from the spot of light onthe second object, electrically operated means controlled by the lightsensitive means, and means for energizing the electrically operatedmeans comprising a lead for connecting the electrically operated meansto one pole of a source of electric current and controlled by the saidcircuit to be intermittently energized at a predetermined frequency, anda second lead for connecting the electrically operated means to a sourceof electric current and controlled by the light sensitive means.

EDWARD BRULIN.

